Electron spectrum in 10-1000 gev from bets & ppb-bets and future balloon observation

We carried out electron observations with balloons to investigate acceleration and propagation of electrons in the universe. We developed BETS (Balloon-borne Electron Telescope with Scintillation fibers) for electron observations in Sanriku. We obtained electron energy spectrum from 10 to 100 GeV with it. At higher energies, the energy spectrum of electron might show some structure caused by nearby sources like the Vela supernova remnant. In order to observe the energy spectrum above 100 GeV, we needed a thicker calorimeter and a longer observation time. We developed PPB-BETS (Polar Patrol Balloon-BETS) by improving BETS to carry out a long duration ballooning in Antarctica. Energy spectrum of electrons from 100 to 1000 GeV was obtained by a successful fight for 13 days. The arrival direction of electrons seems to be consistent with isotropic distribution for the data taken with PPB-BETS, although we need better statistics to make it clear. We have a future plan to make an observation of electrons and gam...